Hydrophobic starch having near-neutral dry product pH

ABSTRACT

A free-flowing, hydrophobic starch composition has a near-neutral dry product pH. Methods for making the hydrophobic starch composition by preparing an aqueous mixture comprising a starch, a siliconate, and an acid, where the aqueous mixture has a near-neutral pH, and drying the starch solids to obtain a hydrophobic starch. Novel fuel compositions comprise hydrophobic starch which can be used in internal combustion engines, such as diesel engines. Hydrophobic starch compositions may be used as fuels or fuel components. Novel methods of fueling and operating internal combustion engines use hydrophobic starch as fuel or fuel components.

This invention relates to novel hydrophobic starch compositions havingnear-neutral dry product pHs and to novel methods of making and usingthose starch compositions. This invention also relates to novel fuelsand fuel components comprising hydrophobic starch compositions.

BACKGROUND OF THE INVENTION

Free-flowing, hydrophobic starches are known in the art and have beenused as dusting materials, dry lubricants, and detackifying agents. U.S.Pat. No. 2,961,339 (Wolff et al.) discloses a free-flowing modifiedstarch and methods for preparing the starch by treating with alkylsiliconates. Wolff '339 purportedly discloses a siliconated granularstarch which is water-repellant and completely free of undesirablealkalinity. Wolff '339 states that an improved starch is made by dryingthe starch before washing, so the water-repellant or hydrophobic qualityis fixed but the alkalinity is not fixed and may be removed by washing.

U.S. Pat. No. 3,071,492 (Satterly) discloses a free-flowing hydrophobicstarch and methods of manufacturing the starch by treating starch in awater slurry with a water-soluble silicone such as monosodium methylsiliconate. Satterly '492 states that its resultant product has dry flowcharacteristics not found in any raw starch or other starch product, andthe flow characteristics resemble those of a fluid rather than a solid.

Wolf '339 and Satterly '492 do not expressly discuss the alkalinity ofthe slurry or resulting product. In the methods described by both Wolff'339 and Satterly '492, the aqueous mixture of the starch and sodiummethyl siliconate would have a highly alkaline pH (e.g., a pH of 12 orhigher) due to the siliconate. The free-flowing, hydrophobic starcheswould have a highly alkaline dry product pH.

Canadian Patent No. 726,667 (Speakman) describes free-flowing,hydrophobic starch and methods of preparation. Speakman '667 discusses amethod of treating granule starch with an alkali metal alkyl siliconateto produce a powdered product having high mobility and hydrophobicityand possessing free acidity. Speakman '667 states that a highly mobile,hydrophobic starch product can be produced by mixing an aqueous solutionof an alkali metal alkyl siliconate with an aqueous suspension ofgranular starch, adjusting the pH of the mixture to a low value by theaddition of an acid, filtering off the starch without washing, dryingthe starch cake, and grinding to reduce the product to a powder.

Speakman '667 teaches that Wolff '339 and Satterly '492 operated at ahighly alkaline pH and produced highly alkaline starch products. Indiscussing Wolff '339, the Speakman '667 patent states, “Even afterwashing and redrying, the products exhibit a high alkalinity.” Indiscussing Satterly '492, the Speakman '667 patent states, “Finally, thefree-flowing hydrophobic products made by this method have appreciablealkalinity, as shown by pH values of 10 or greater of mixtures of theproduct and water after vigorous shaking.”

The Speakman '667 patent discloses adjusting the pH of an aqueousmixture of siliconate and starch to a low value by the addition of anacid. In a specific example, the pH of the mixture was adjusted to 2.5using hydrochloric acid. The resulting starch had a dry product pH of2.6. The Speakman '667 patent states, “It is possible to providefree-flowing hydrophobic starches having acidic or alkaline levelsanywhere in a wide range by intimately mixing finely powdered alkalineproducts made by the methods of the prior art and acidic products madeby the present invention.”

The known methods of preparing free-flowing hydrophobic starch productsresult in starch products which are highly alkaline or highly acidicwhen dispersed in water. The high alkalinity or high acidity of knownstarch products when dispersed in water poses the possibility that thesestarch products might, under some conditions, corrode some materialswith which they come into contact. The potential for corrosion limitsthe desirability of these known methods and compositions wherecorrosivity is a concern.

While the methods listed above are useful for preparing free-flowinghydrophobic starch, there is a need for a free-flowing hydrophobicstarch whose dry product pH is near-neutral.

BRIEF SUMMARY OF THE INVENTION

As one aspect of the present invention, novel methods are provided forpreparing a hydrophobic starch having a near-neutral dry product pH. Themethod comprises preparing an aqueous mixture comprising a starch, asiliconate, and an acid, wherein the aqueous mixture has a near-neutralpH. The near-neutral pH can be achieved in the aqueous mixture byincluding a suitable amount of acid in the aqueous mixture. Starchsolids in the aqueous mixture can be separated by filtering or othermeans, preferably without washing. Starch solids from the aqueousmixture are dried to form a hydrophobic starch. The dried starch solidscan be subjected to grinding or another powderizing step.

The aqueous mixture having a near-neutral pH and comprising the starchand the siliconate can be prepared in a number of ways. For example, thestarch and the siliconate can be combined in the aqueous mixture beforecombining with an acid. An acid can then be added to the aqueous mixturein an amount sufficient to adjust the pH of the aqueous mixture to anear-neutral pH. As another example, the siliconate and the acid can becombined to form an aqueous solution before combining with the starch.The aqueous solution can have a near-neutral pH when the starch iscombined.

As another aspect of the invention, novel hydrophobic starchcompositions are provided which are free-flowing, hydrophobic, and havea near-neutral dry product pH. Yet another aspect of the inventionincludes reaction products from the manufacturing methods describedherein. For example, a novel hydrophobic starch composition comprisesthe reaction product of a starch, a siliconate, and an acid, mixed at anear-neutral pH, filtered, and dried to a desired moisture content.Preferably, the reaction product is obtained without washing. The dryproduct pH of the novel starch compositions and reaction products can bebetween about 6.9 and about 7.6 or another desirable pH range. dryproduct pH. Yet another aspect of the invention includes reactionproducts from the manufacturing methods described herein. For example, anovel hydrophobic starch composition comprises the reaction product of astarch, a siliconate, and an acid, mixed at a near-neutral pH, filtered,and dried to a desired moisture content is provided herein. Preferably,the reaction product is obtained without washing. The dry product pH ofthe novel starch compositions and reaction products can be between about6.9 and about 7.6 or another desirable pH range.

As another aspect, methods are provided for fueling an internalcombustion engine which comprises feeding to the engine under combustionconditions a fuel comprising a hydrophobic starch. As yet anotheraspect, methods are provided for operating an internal combustion engineusing a hydrophobic starch as a fuel or a fuel component. For example,the engine can be a diesel engine or an engine that has a spark plug.The methods can include introducing a fuel comprising a free-flowing,hydrophobic starch into a combustion chamber of the engine. The methodscan also include introducing sufficient air to the chamber forcombustion, and igniting the free-flowing, hydrophobic starch as a fuelfor the engine. The fuel or fuel component can be a free-flowing,hydrophobic starch having a near-neutral pH, or one of the highlyalkaline or highly acidic free-flowing, hydrophobic starches of theprior art.

As yet another aspect, novel fuels and fuel components are provided. Thefuels and fuel components include a hydrophobic starch. Preferably,fuels and fuel components include a free-flowing, hydrophobic starchhaving a near-neutral dry product pH.

The novel free-flowing hydrophobic starch compositions described hereinmay be used in the conventional ways or in new ways, as described indetail herein. For example, the free-flowing, hydrophobic starchcompositions having near-neutral dry product pH can be used as dustingmaterials, dry lubricants, and detackifying agents. As another example,the free-flowing, hydrophobic starch compositions are useful as fuels orfuel components for internal combustion engines. As such, thefree-flowing, hydrophobic starch compositions constitute a feasible andsensible alternative to petroleum-based fuels, since a fuel or fuelcomponent can be obtained from the inexpensive starch slurry producedduring the routine processing operation of conventional wet cornmilling. Additionally, the low production cost and lack of free acidityor alkalinity of the novel hydrophobic starch compositions having anear-neutral dry product pH reduces potential corrosiveness. This makesit a superior choice to the prior hydrophobic free-flowing starches inapplications such as rubber dusting, dry lubrication, or detackifying.Moreover, the combustion products of the novel hydrophobic starchcomposition, being of near-neutral pH, will have little or nocorrosivity.

DETAILED DESCRIPTION OF THE INVENTION

The compositions and methods described herein relate to the novelpreparation of a free-flowing, hydrophobic starch having near-neutraldry product pH. The hydrophobic starch has polymerized siliconate on thestarch surface which tends to maintain low moisture content as well asmobility. Thus, a free-flowing, hydrophobic starch has less tendency toabsorb moisture which would decrease mobility. A composition will beconsidered free-flowing when it has equal or better mobility than finelyground starch. An impalpable powder having a sufficiently low moisturecontent will generally be free-flowing.

Near-neutral pH is neither highly acidic nor highly alkaline. Forexample, near-neutral pHs include pHs between about 6 and about 8. Thefree-flowing, hydrophobic starches prepared in Wolff '339, Satterly'492, and Speakman '667 do not have near-neutral dry product pHs. Thedry product pH of a composition refers to the pH of an aqueous mixturewhen the composition is mixed in water at a concentration of 10 g of thecomposition in 50 ml of distilled water. The present disclosure providestechniques for making hydrophobic starch compositions having dry productpHs greater than 6 or about 6, alternatively greater than 5 or about 5,alternatively greater than 4 or about 4, alternatively greater than 3 orabout 3, alternatively greater than 2.6. The present disclosure providestechniques for making hydrophobic starch compositions having dry productpHs less than 8 or about 8, alternatively less than 9 or about 9,alternatively less than 10 or about 10, alternatively less than 11 orabout 11, alternatively less than 12. Any of the minimum and maximum pHsset forth above may be combined to define a pH range.

The present techniques for making hydrophobic starch compositions usestarches, siliconates and acids. Starches suitable for use hereininclude corn starch, potato starch, tapioca starch, wheat starch, ricestarch, sorghum starch, and the like, as well as combinations of any ofthe foregoing. Starches are polymeric chains of glucose units. Naturalstarches from plants are mixes of two types of polymeric chains calledamylose and amylopectin, in which the monomers are glucose units joinedto one another head-to-tail forming alpha-1,4 linkages. Amylose is alinear polymer of glucose linked with α(1→4) bonds. Amylopectin is ahighly branched polymer of glucose found in plants. Its glucose unitsare linked in a linear way with α(1→4) bonds, but branching takes placewith ═(1→6) bonds occurring each 24 to 30 glucose units. The relativecontent of amylose and amylopectin varies between different species ofstarch.

Starch is generally produced by milling an agricultural product that isa source of starch (for example, corn, potatoes, tapioca, wheat, rice,sorghum, and the like). The product of milling is processed to removefibers, proteins, and soluble material.

Alkyl siliconates, in the form of the alkali metal salt, have been knownas agents for imparting water resistance or water repellency to a widevariety of substrates such as masonry, water-based paint ingredients,powdered materials such as limestone, gypsum, and the like, paper,paperboard, and various textiles. Siliconates are sometimes referred toas silanolates or salts or siliconic acids.

Siliconates include organosiliconates such as alkyl siliconates andphenyl siliconates, and salts thereof. The preferred salts are sodiumand potassium salts. Alkali metal alkyl siliconates include thosedefined by the general formula:

where R is an alkyl group containing 1 or more carbons and X is analkali metal. The preferred alkali metal alkyl siliconate is sodiummethylsiliconate, where R is a methyl group and X is sodium orpotassium. Exemplary species of alkali metal organosiliconates includesodium methylsiliconate, sodium ethylsiliconate, sodiumpropylsiliconate, potassium methylsiliconate, potassium ethylsiliconateand potassium propylsiliconate.

Suitable acids include hydrogen-donating acids, for example,hydrochloric, sulfuric, nitric, phosphoric, and acetic acids. Apreferred acid is hydrochloric acid.

The starches, siliconates and acids can be used in the following methodsto make free-flowing, hydrophobic starch compositions. An aqueousmixture of starch, siliconate and acid is prepared in any suitablemanner. For example, an aqueous slurry of corn starch can be preparedfrom dry substance granule corn starch, and a siliconate can be combinedto form an aqueous mixture comprising the starch and the siliconate. Theaqueous mixture can be adjusted to a desired near-neutral pH with theaddition of a suitable amount of an acid. Alternatively, the aqueousmixture can be made by a method where a siliconate, preferably sodiummethylsiliconate, is combined with an acid in an aqueous solution beforecombining the starch to form an aqueous mixture. In other words, anaqueous solution can be made from a siliconate and an acid, and thesolution can be adjusted to a desired near-neutral pH with a suitableamount of acid.

Typical concentrations of starch in an aqueous slurry include the rangeof about 30% to about 39% by weight. Any appropriate starch may be used,though untreated corn starch is often preferred for reasons of economyor availability. The slurry can then be agitated by any suitable means.For example, variable or high speed propeller agitators or other typesof mixing equipment can be used to agitate the slurry.

As mentioned above, the siliconate can be added to an aqueous slurrycomprising starch to form an aqueous mixture of starch and siliconate,or the starch can be added to an aqueous solution comprising thesiliconate. The siliconate can be combined with the starch slurry byitself or in combination with an acid. The amount of siliconate can beselected as a proportion of the amount of starch. For example, theconcentration of the metal alkyl siliconate preferably will beapproximately 0.05% to 5%, alternatively about 0.5% to 1.0%,alternatively about 0.8% by weight compared to the starch.

The pH of the aqueous mixture is adjusted to a desired pH by adding anacid. The pH can be adjusted to a near-neutral pH. The pH can beadjusted to a pH greater than 4 and less than about 10, alternativelybetween about 5 and about 9, alternatively between about 6 and about 8,alternatively between about 6.5 and about 7.5, alternatively betweenabout 6.8 and about 6.9, using an acid which dissociates sufficiently inwater to produce the desired pH.

The aqueous mixture having a near-neutral pH and comprising the starchand the siliconate is agitated for a suitable period, for example atleast 30 minutes, although agitation can continue for longer or shorterperiods. The starch can then be separated from the aqueous mixture byany effective means, such as by filtration, to obtain starch solids (thewet filter cake resulting from filtration).

The wet filter cake (the starch solids) is then dried to a suitablemoisture content to obtain dried starch solids. For example, the filtercake may be dried to a minimum moisture content, such as a moisturecontent of at least about 6%, alternatively at least about 7%,alternatively at least about 8%, alternatively at least about 9%,alternatively at least about 10%. As another example, the filter cakemay be dried to a maximum moisture content, such as at most about 11%,alternatively at most about 12%, alternatively at most about 13.5%. Theforegoing minimum and maximum moisture contents may be combined to formranges.

Drying promotes polymerization of the siliconate, which provides and/orcontributes to free-flowing and hydrophobic attributes. Therefore, it iscontemplated that the present methods may comprise polymerizing (ratherthan drying) at least some of the siliconate on at least some of thestarch to form a hydrophobic starch. However, drying is the mostconvenient and practical technique for polymerizing at least some of thesiliconate and for obtaining a starch composition having a desiredmoisture content. Drying temperatures in the range of 160 to 210 degreesFahrenheit are preferred for drying, though other suitab temperatures,pressures and conditions can also be used and are easily determined.

The dried filter cake (dried starch solids) can then be powderized, suchas by grinding or pulverizing, or by sieving the dried starch solids toremove oversize or non-powder material. The wet filter cake beforepowderizing does not have to be washed, nor does the powder have to bewashed. The powder is hydrophobic and free-flowing, and has anear-neutral dry product pH. The method can also include the steps ofadjusting the pH of the aqueous mixture with one or more acids,filtering off the starch without washing, drying the starch, thengrinding and screening the resulting starch product through a sieve.

As another aspect, free-flowing, hydrophobic starch compositions can beused as a fuel or a fuel component for an internal combustion enginesuch as a vehicle engine or a generator, including gasoline engines,diesel engines, jet engines, and others. A fuel for an internalcombustion engine may consist essentially of a free-flowing, hydrophobicstarch composition. In such a fuel, the hydrophobic starch compositionis the main source of combustion. Alternatively, a fuel may comprise ahydrophobic starch composition as one fuel component along with otherfuel components such as gasoline, diesel, kerosene, or jet fuels. Insuch a fuel, the hydrophobic starch is one combustible, and one or moreother combustibles. Other possible fuel components are alcohols. Theforegoing fuels and fuel components may also include detergents, anddeposit control agents, as well as various other fuel additives known inthe automotive field.

When used in a gasoline internal combustion engine, a fuel comprising ahydrophobic starch is mixed with air in a carburetor and passed to thecylinder, or is introduced by an injector into the cylinder, where aspark plug is timed to generate a spark to ignite a fuel/air mixture. Apiston in the cylinder moves axially in a stroke, providing rotationalmotion to a crank shaft via a connecting rod.

When used in a diesel engine, a fuel comprising a hydrophobic starch isinjected into compressed air in an engine cylinder, and the heat of thecompressed air ignites the fuel (although a glow plug or other ignitiondevice may be used under some circumstances, such as when the engine iscold). Diesel engines use direct fuel injection—the diesel fuel isinjected directly into an engine cylinder by an injection system.Injection systems are known in the art for providing fuel powders toengines.

When used in a jet engine, a fuel comprising a hydrophobic starch iscombined with air drawn in at the front which has been compressed. Thefuel combined with air is typically ignited by a flame in the eddy of aflame holder, and burned as an atomized mixture. The combustion greatlyincreases the energy of the gases which are then exhausted out of therear of the engine. The jet engine generates thrust because of theacceleration of the air through it—the equal and opposite force thisacceleration produces is thrust.

The internal combustion engine fueled by free-flowing hydrophobic starchcompositions can be used in a wide variety of vehicles and equipment.For example, internal combustion engines fueled by the present fuels andfuel components can power automobiles, trucks, lawn mowers, tractors,farm machinery, trains, marine engines, fire pumps, power generators,jet engines, industrial equipment such as chippers and air compressors,locomotives, mining machinery, and others. This is not an exhaustivelist, and it is contemplated that free-flowing, hydrophobic starchcompositions are suitable for any use or application of an internalcombustion engine.

Free-flowing, hydrophobic starch compositions can be used in standardinternal combustion engines, or an engine or its associated equipment(for example, ignition devices or fuel injectors) which may be modifiedusing routine engineering principles to be more suitable for operationusing a free-flowing hydrophobic starch composition as a fuel. The useof powdered or particulate fuels for internal combustion engines hasbeen described in the public literature such as, for example, U.S. Pat.No. 3,981,277 (Abom), U.S. Pat. No. 4,052,963 (Stieger), U.S. Pat. No.4,070,997 (Stieger), U.S. Pat. No. 4,359,970 (Wolters), and U.S. Pat.No. 5,056,469 (Kimberley). Furthermore, powdered or particular fuels ofappropriate size can be used in existing common-rail injection systems,which are currently used with diesel engines and may also be used withgasoline engines. It is believed that free-flowing, hydrophobic starchcompositions have not previously been suggested as fuels or fuelcomponent for internal combustion engines.

Where a fuel is provided as a free-flowing powder or particulate slurry,it is desirable that the fuel has particles having an appropriatelysmall particle size. A fuel provided as a free-flowing powder orparticulate slurry may be used in place of or in combination with aliquid fuel in an internal combustion engine such as a diesel engine.Such fuels may be in the form of a powder and comprise or consistessentially of a free-flowing hydrophobic starch. Alternatively, suchfuels may be provided in fluid form, such as by suspending a hydrophobicstarch in liquid or gelled gasoline or kerosene. For example, afree-flowing, hydrophobic starch may be included as a fuel component ina gelled fuel for a jet engine and could provide a significantproportion of the heat of combustion of the fuel.

Fuels comprising free-flowing, hydrophobic starch compositions may havevarious advantages over other fuels in terms of cost and convenience inhandling and manufacture. Powder fuels are likely to be easier to handlethan liquid fuels. A free-flowing, hydrophobic starch can be lessexpensive than ethanol as a fuel, in terms of energy produced divided bycost of production. In general, it is desirable to provide a fuel powderin very finely divided form, such as of a size to pass through a 200mesh screen or a 150 mesh screen. This fuel powder can be aspirated intoa combustion cylinder of the internal combustion engine on a suctionstroke. At the end of the compression stroke, the fuel powder can beignited, such as by the heat of a compression or by a spark generatingelement, and thereby the fuel is caused to burn and produce a powerstroke of the engine's piston. In a diesel engine, the fuel is generallyignited by the heat of the compressed air, though a glow plug is usedwhen the engine is cold.

The near-neutral pH, free-flowing, hydrophobic starch compositionsdescribed herein are contemplated for use as fuels in operating internalcombustion engines. It is also contemplated that other free-flowinghydrophobic starch compositions, such as those described in Wolff '339,Satterly '492, and Speakman '667, may be used as fuels or fuelcomponents in internal combustion engines. However, free-flowing,hydrophobic starch compositions having a near-neutral dry product pH maybe more desirable as fuels and fuel components than the free-flowing,hydrophobic starch compositions of the prior art. The hydrophobic starchcompositions having a near-neutral dry product pH are less likely tocorrode or otherwise damage engine parts, than prior art compositionswhich are highly alkaline or highly acidic.

Specific examples of various aspects of the invention are provided belowsolely for information and education and are not intended to delineatethe scope of the invention nor limit the claims. In the examples andthroughout this specification, percentages are intended to refer topercent by weight, unless otherwise indicated.

EXAMPLE 1

Dry unmodified corn starch was suspended in water to create a slurry of500 mL total volume, containing 210.7 g of starch and 375 g of water.

3.29 g of an aqueous solution of sodium methylsiliconate was added tothe starch slurry to create an aqueous mixture. The added solutioncontained 1.053 g of siliconate solids. The sodium methylsiliconate wasprovided as 0.5% siliconate solids by weight compared to the dry starch.The pH of the mixture was adjusted to 6.88 using hydrochloric acid.

The mixture was agitated at room temperature for 30 minutes. The pH wasmeasured again to verify that the mixture was in a near-neutral pHrange. The pH was 6.68 at the second measurement. The wet starch solidswere recovered by filtration on a Buchner funnel. The wet starch solidswere not washed.

The filter cake was then dried in a conventional oven at about 180° F.for approximately 4 hours. After drying, the dried starch solids wereground in a roller mill to pass a 150 mesh copper wire screen. Afree-flowing, hydrophobic starch having a near-neutral dry product pHwas obtained.

EXAMPLE 2

10 g of the free-flowing, hydrophobic starch composition prepared inExample 1 was placed in 50 mL of distilled water and shaken vigorouslyfor 10 minutes. The pH of this mixture was measured and found to be6.90. The pH determined in this manner is the “dry product pH” of thehydrophobic starch composition. Thus, the free-flowing, hydrophobicstarch from Example 1 had a dry product pH of 6.90.

EXAMPLE 3

A hydrophobic starch is used as a fuel for an internal combustionengine. A free-flowing hydrophobic starch is introduced to the fuel tankof a diesel vehicle. The Siemens VDO common-rail injection system fordiesel engines has injectors that would permit injection of a powderpassed through a 150 mesh screen. A free-flowing, hydrophobic starchcomposition that is a powder with particle sizes less than 150 mesh isused as a fuel with such a system. The free-flowing, hydrophobic starchcomposition is used as a fuel for an internal combustion engine. Thefuel is provided to the engine in free-flowing form and is aspiratedinto a cylinder on a suction stroke. The fuel is heated by compressionto a point at which the finely divided material is ignited by the heatof compression, or by an ignition source such as a glow plug when theengine is cold.

All patents, test procedures, and other documents cited herein are fullyincorporated by reference to the extent such disclosure is notinconsistent with this invention and for all jurisdictions in which suchincorporation is permitted.

While the present invention has been described and illustrated byreference to particular embodiments, it will be appreciated by those ofordinary skill in the art that the invention lends itself to manydifferent variations not illustrated herein. For these reasons, then,reference should be made solely to the appended claims for purposes ofdetermining the true scope of the present invention.

Although the dependent claims have single dependencies in accordancewith U.S. patent practice, each of the features in any of the dependentclaims can be combined with each of the features of other independent ordependent claims.

1. A method of preparing a hydrophobic starch, wherein the methodcomprises: preparing an aqueous mixture comprising a starch, asiliconate, and an acid, wherein the aqueous mixture has a pH that isbetween 5 and 8; and drying starch solids separated from the aqueousmixture to form a hydrophobic starch.
 2. The method of claim 1 whereinthe starch and the siliconate are prepared in the aqueous mixture andthen the acid is added to the aqueous mixture in an amount sufficient toadjust the pH of the aqueous mixture to a pH that is between 5 and
 8. 3.The method of claim 1 wherein an aqueous solution comprising thesiliconate and the acid is prepared before combining the siliconate withthe starch, wherein the aqueous solution has a pH that is between 5 and8 when the starch is combined with the siliconate.
 4. The method ofclaim 1 comprising filtering starch solids from the aqueous mixturebefore drying.
 5. The method of claim 1 comprising drying the starchsolids to a moisture content from about 6% to about 15%.
 6. The methodof claim 5 wherein the starch solids are dried to a moisture contentfrom about 10% to about 13.5%.
 7. The method of claim 1 comprising thestep of powderizing the dried starch solids.
 8. The method of claim 1wherein the pH of the aqueous mixture is between 6 and
 8. 9. Thereaction product of the process of claim
 1. 10. The method of claim 1wherein the aqueous mixture has a pH that is between 6.5 and 7.5. 11.The method of claim 1 wherein the aqueous mixture has a pH that isbetween 6.8 and 6.9.
 12. The method of claim 1 wherein the aqueousmixture has a pH that is 6.90.
 13. A hydrophobic starch compositioncomprising a reaction product of a starch, a siliconate, and an acid,and having a dry product pH that is between 5 and
 8. 14. The hydrophobicstarch composition of claim 13 wherein the dry product pH is between 6and
 8. 15. The hydrophobic starch composition of claim 13 wherein thedry product pH is at least 6.9 and at most 7.6.
 16. The hydrophobicstarch composition of claim 13 wherein the dry product pH is between 6.5and 7.5.
 17. The hydrophobic starch composition of claim 13 wherein thedry product pH is between 6.8 and 6.9.
 18. The hydrophobic starchcomposition of claim 13 wherein the dry product pH is 6.90.